1. Field of the Invention
The present invention relates to a single-lens reflex camera having data-transmission pins (contact members) at positions other than on the lens mount surface thereof; and in particular, to a photographic lens, a camera body and a camera system of a medium-format single-lens reflex camera.
2. Description of the Related Art
In single-lens reflex cameras of the prior art, a contact pin group (a lens pin group) at a position other than the lens mount surface of the photographic lens thereof has been provided (for example at an inside part of the lens mount surface) having a plurality of contact pins in order to identify open aperture data and minimum aperture data. A corresponding contact pin group (body pin group) having a plurality of contact pins which make contact with the lens pin group is provided in the vicinity of a lens mount surface of the camera body. The electric potential (level) at these contact pin groups are checked; subsequently, the open aperture data and the minimum aperture data are input in the camera body.
Recently, there has been requirements for functions that are not provided in photographic lenses or camera bodies of the prior art. However, when a photographic lens or a camera body is to be equipped with additional new functions, there arises a problem of compatibility between pre-existing and new photographic lenses or camera bodies; in particular, the compatibility of the contact members and the communication system which carries out data transmission between the photographic lens and the camera body.
FIGS. 4 and 5 are examples of lens mounts of a photographic lens and a camera body of the prior art. The aperture data setting pin group (a contact pin group) includes a series of lens pins 75a, 75b, 75c, 75d, 75j, 75k and 751. The lens pins 75a through 75d and 75j through 75l are aligned in a circle, the center of which lies on the optical axis of photographic lens 71 closer to the optical axis than mount ring 72 and bayonet plate 73 (i.e., inside the concentric circles of the mount ring 72 and the bayonet plate 73) of the photographic lens 71. The aperture data is transmitted from the lens pins 75a, 75b, 75c, 75d, 75j, 75k and 75l to corresponding body pins 55a, 55b, 55c, 55d, 55j, 55k and 55l, which serve as data-transmission pins, in order to be read by a camera body 51. The body pins 55a through 55d and 55j through 55l are also aligned in a circle, the center of which lies on the optical axis of the camera body 51, closer to the optical axis than mount ring 52 or bayonet plate 53 (i.e., inside the concentric circles of the mount ring 52 and the bayonet plate 53) of the camera body 51. Each of the lens pins 75a through 75d and 75j through 75l is fixed on a protection ring 74 made of an insulating material, each protruding from each hole therefor formed in the protection ring 74. Each of the body pins 55a through 55d and 55j through 55l is also fixed on a pin supporting plate 56 made of an insulating material, each protruding from each hole therefor formed in the pin protection plate 56. A spring force is applied to each of the body pins 55a through 55d and 55j through 55l by a spring (not shown), whereby the body pins 55a through 55d and 55j through 55l can protrude from the pin supporting plate 56 or sink therein. Furthermore, the mount ring 52 and the bayonet plate 53 of the camera body 51 and the mount ring 72 and bayonet plate 73 of the photographic lens 71 are all formed from metal. Consequently, when the photographic lens 71 is attached to the camera body 51, each mount ring (72 and 52 respectively) and each bayonet plate (73 and 53 respectively) make contact with each other, wherein the electric potential level thereof becomes the same as ground.
However, when the above-mentioned photographic lens is equipped with new functions such as ROM, an AF motor and a controller therefor, or a lens shutter and a controller therefor; sufficient data or command communication relating to such new functions cannot be carried out using pre-existing, former lens pins 75a through 75d and 75j through 75l and body pins 55a through 55d and 55j through 55l. Furthermore, though a new-designed photographic lens having additional lens pins can be matched with a new-designed camera body also having additional body pins, if such a new (designed) photographic lens having additional lens pins is attached to a pre-existing camera body, the additional lens pins cannot make contact with any member of the pre-existing camera body. Therefore it is impossible to carry out data or command communication between the new photographic lens and the pre-existing camera body. In other words, the pre-existing camera body cannot recognize the new commands of the new photographic lens.
It is an object of the present invention to provide a photographic lens, a camera body and a camera system having additional new functions, which are compatible with a pre-existing photographic lens, camera body and camera system.
To achieve the object mentioned above, according to the present invention, there is provided a camera body which includes: a plurality of body contact-members which can be in contact with, and electrically connected to, a plurality of lens contact-members of a photographic lens when the photographic lens is attached to the camera body; a communication device which can carry out a first communication for receiving fixed information and also a second communication for transmitting arbitrary information, wherein the first communication is carried out via a predetermined body contact-member group-A chosen from the plurality of body contact-members when a photographic lens which allows the first communication is attached; and wherein the second communication is carried out via a predetermined body contact-member group-B, the body contact-member group-B including the predetermined body contact-member group-A chosen from the plurality of body contact-members when a photographic lens allowing the second communication is attached to the camera body; and an identifying device which determines whether or not an attached photographic lens allows the second communication, via predetermined first and second body contact-members selected from the plurality of body contact-members not belonging to the predetermined body contact-member group-A. The communication device communicates with the attached photographic lens via the second communication when the identifying device identifies the attached photographic lens to be a photographic lens which allows the second communication, and via the first communication when the identifying device identifies that the attached photographic lens is a photographic lens allowing the first communication. The predetermined first and second body contact-members become insulated from each other when the photographic lens allowing the second communication is not attached to the camera body; and wherein the predetermined first and second body contact-members become electrically connected to each other via corresponding lens contact-members of the attached photographic lens. The corresponding lens contact members are in contact with the predetermined first and second body contact-members of the camera body, respectively, when the photographic lens which allows the second communication is attached.
Preferably, the identifying device determines whether or not the attached photographic lens allows the second communication by comparing the electric potential of one of the predetermined first and second body contact-members with the electric potential of the other of the predetermined first and second body contact-members.
Preferably, the camera body supplies electric power to the attached photographic lens via one of the predetermined first and second body contact-members when the identifying device determines that the attached photographic lens allows the second communication.
Preferably, the second communication is carried out with the photographic lens via the predetermined body contact-member group-B when the camera body supplies electric power to the photographic lens via the predetermined second body contact-member.
Preferably, the plurality of body contact-members include contact members used both for the first communication and for the second communication.
Preferably, the positions of the plurality of body contact-members are closer to the optical axis of the attached photographic lens than the position of a body mount to which the photographic lens is attached. The predetermined first and second body contact-members are positioned adjacent to each other.
Preferably, the communication device inputs characteristic information of the attached photographic lens via the body contact-member group-A when the identifying device determines that the attached photographic lens allows the first communication.
According to another aspect of the present invention, there is provided a photographic lens which includes: a plurality of lens contact-members which can be in contact with, and electrically connected to, a plurality of body contact-members of a camera body when the photographic lens is attached to the camera body; a communication device which can carry out a first communication for transmitting fixed information and also a second communication for transmitting arbitrary information; wherein characteristic information of the photographic lens is transmitted to the camera body through various combinations of electric potentials of the predetermined lens contact-member group-A chosen from the plurality of lens contact-members when the photographic lens is attached to a camera body which allows the first communication. When the second communication is carried out via a predetermined lens contact-member group-B chosen from the plurality of lens contact-members, the photographic lens is attached to a camera body allowing the second communication; and a transmission member which transmits information to convey to the camera body which allows the second communication that the attached photographic lens is a photographic lens which allows the second communication via predetermined first and second lens contact-members; the first and second lens contact-members not belonging to the predetermined lens contact-member group-A. The transmission member electrically connects at least one of the first and second lens contact-members to a ground member of the photographic lens when the photographic lens is not attached to the camera body which allows the second communication; and wherein the transmission member moves away from the ground member when the photographic lens is attached to the camera body which allows the second communication; whereby the transmission member is insulated from the first and lens contact members.
Preferably, the transmission member further includes an electric connection member which electrically connects the predetermined first lens contact-member to the predetermined second lens contact-member, and when the photographic lens is attached to the camera body which allows the second communication, the predetermined first and second lens contact-members are both insulated from the ground member whereby the camera body which allows the second communication can identify that the photographic lens which allows the second communication has been attached to the camera body.
Preferably, the predetermined first lens contact-member is a movable lens contact-member attached to an insulating support plate, the insulating support plate supporting the plurality of lens contact-members whereby the movable lens contact-member is forwardly and rearwardly movable in a direction substantially parallel to the optical axis of the photographic lens and protrudes from the insulating support plate via a force applied to the movable lens contact-member. The movable lens contact-member protrudes from the insulating support plate in order to make contact with the ground member when the photographic lens is not attached to the camera body which allows the second communication, and the movable lens contact-member is pushed by a predetermined camera contact-member to be moved away from the ground member when the photographic lens is attached to the camera body which allows the second communication.
Preferably, the predetermined first and second lens contact-members are provided adjacent to each other, the electric connection member is fixed to the predetermined second lens contact-member, and the predetermined first lens contact-member is pushed toward the protrusive direction by a spring member made of a conductive material positioned in a space between the predetermined first lens contact-member and the electric connection member.
Preferably, when the photographic lens is attached to the camera body which allows the second communication, the predetermined second lens contact-member comes in contact with a predetermined camera contact-member of the camera body which allows the second communication in order to receive power supply from the camera body which allows the second communication, thereby the communication device carries out the second communication.
Preferably, the plurality of lens contact-members include contact members used both for the first communication and for the second communication.
Preferably, the plurality of lens contact-members are provided closer to the optical axis of the photographic lens than the position of a lens mount used for mounting on the camera body; the predetermined first and second lens contact-members being positioned adjacent to each other.
Preferably, the lens contact-member group-A chosen from the plurality of lens contact-members for carrying out the first communication and the predetermined first lens contact-member are selectively connected to each other via a diode, and when the photographic lens is attached to the camera body which allows the first communication, each contact member of the lens contact-member group-A connected to the predetermined first lens contact-member via the diode becomes electrically connected to the ground member via the specified first lens contact-member, whereby characteristic information of the photographic lens is transmitted to the camera body which allows the first communication. Preferably, the diode is a Schottky barrier diode.
According to another aspect of the present invention, there is provided a camera system including a detachable photographic lens having a plurality of lens contact-members, and a camera body having a plurality of body contact-members, the plurality of lens and body contact-members being correspondingly in contact with, and electrically connected to, each other when the photographic lens is attached to the camera body. The camera body includes: a body communication-device which can carry out a first communication for receiving fixed information and also a second communication for communicating arbitrary information, wherein the first communication is carried out via a predetermined body contact-member group-A chosen from the plurality of body contact-members when a photographic lens allowing the first communication is attached to the camera body, and wherein the second communication is carried out via a predetermined body contact-member group-B which includes the predetermined body contact-member group-A chosen from the plurality of body contact-members when a photographic lens which allows the second communication is attached to the camera body; and a body identifying device which determines whether or not the attached photographic lens allows the second communication via predetermined first and second body contact-members selected from the plurality of body contact-members not belonging to the predetermined body contact-member group-A. The body communication-device communicates with the attached photographic lens via the second communication when the identifying device determines that the attached photographic lens is a photographic lens which allows the second communication; and via the first communication when the identifying device determines that the attached photographic lens is a photographic lens which allows the first communication. The photographic lens includes: a lens communication-device which can carry out the first communication for transmitting the fixed information and also can carry out the second communication for transmitting the arbitrary information; wherein, when the photographic lens is attached to a camera body which allows the first communication, characteristic information of the photographic lens is transmitted to the camera body which allows the first communication through various combinations of electric potentials of a predetermined lens contact-member group-A chosen from the plurality of lens contact-members; and when the photographic lens is attached to a camera body allowing the second communication, the second communication is carried out via a predetermined lens contact-member group-B chosen from the plurality of lens contact-members; and a transmission member which transmits information to convey to the camera body which allows the second communication that the attached photographic lens is a photographic lens which allows the second communication via predetermined first and second lens contact-members not belonging to the predetermined lens contact-member group-A.
Preferably, the body identifying device determines, via the predetermined first and second body contact-members and the corresponding predetermined first and second lens contact-members, that an attached photographic lens is the photographic lens which allows the second communication when the photographic lens is attached to the camera body; wherein the second communication between the body communication-device and the lens communication-device is carried out via the predetermined body contact-member group-B and via the predetermined lens contact-member group-B.
Preferably, the predetermined first and second body contact-members of the camera body become insulated from each other when the photographic lens which allows the second communication is not attached to the camera body, and the predetermined first and second body contact-members of the camera body become electrically connected to each other via corresponding lens contact-members of the attached photographic lens to be in contact with the predetermined first and second body contact-members of the camera body, respectively, when the photographic lens which allows the second communication is attached to the camera body; and at least one of the predetermined first and second lens contact-members of the photographic lens is electrically connected to a ground member of the photographic lens when the photographic lens is not attached to the camera body which allows the second communication, and the predetermined first and second lens contact-members are moved away to be insulated from the ground member when the photographic lens is attached to the camera body which allows the second communication.
Preferably, the body identifying device determines whether or not the attached photographic lens allows the second communication by comparing the electric potential of one of the predetermined first and second body contact-members with the electric potential of the other of the predetermined first and second body contact-members, and the photographic lens further including an electric connection member which electrically connects the predetermined first lens contact-member to the predetermined second lens contact-member, and when the photographic lens is attached to the camera body which allows the second communication, the predetermined first and second lens contact-members are both insulated from the ground member whereby the body identifying device of the camera body which allows the second communication can identify that an attached photographic lens is the photographic lens which allows the second communication.
Preferably, the predetermined first lens contact-member of the photographic lens is a movable lens contact-member attached to an insulating support plate which supports the plurality of lens contact-members, wherein the movable lens contact-member is forwardly and rearwardly movable in a direction substantially parallel to the optical axis and protrudes from the insulating support plate by a force applied to the movable lens contact-member; the movable predetermined first lens contact member protrudes from the insulating support plate to be in contact with the ground member when the photographic lens is not attached to the camera body which allows the second communication; and the movable predetermined first lens contact-member is pushed by the predetermined first camera contact-member to be moved away from the ground member when the photographic lens is attached to the camera body which allows the second communication.
Preferably, the camera body supplies electric power to the attached photographic lens via one of the predetermined first and second body contact-members when the body identifying device of the camera body identifies that the attached photographic lens allows the second communication; and the attached photographic lens receives electric power supplied from the camera body via one of the predetermined first and second lens contact-members when the photographic lens is attached to the camera body which allows the second communication; wherein the lens communication-device carries out the second communication.
Preferably, when the photographic lens is attached to the camera body, the body identifying device determines via the predetermined first and second body contact-members and the corresponding predetermined first and second lens contact-members, that the attached photographic lens is the photographic lens which allows the second communication; and the camera body supplies electric power to the photographic lens via one of the predetermined first and second body contact-members and via a corresponding one of the predetermined first and second lens contact-members, wherein the second communication between the body communication-device and the lens communication-device is carried out via the predetermined body contact-member group-B and via the predetermined lens contact-member group-B.
The present disclosure relates to subject matter contained in Japanese Patent Application No.09-336028 (filed on Dec. 5, 1997) which is expressly incorporated herein by reference in its entirety.